The Statistical Office of the Southwest Oncology Group (SWOG) is a unit essential to the conduct of cooperative clinical research by the membership. Its functions are: (1) to provide analyses of on-going clinical studies in cooperation with the chairman of each study; (2) to achieve the objective in (1), provides for the central registration of all patients and studies, and provides for the surveillance, monitoring, storage, and processing of the data collected during Group studies; (3) to provide for the review of all proposed protocols and to suggest an experimental design for each study; (4) to work in close cooperation with the Chairman of the SWOG in the administration of Group studies; (5) to perform research on the statistical aspects of Group studies to improve the efficiency of on-going and future clinical trials; and (6) to carry out long-term analyses of Group studies to determine, for example, whether survival has been improved with time, and which clinical and laboratory variables seem important in relation to the response and survival of a cancer patient.